In Your opinion.. Body language that gives the impression of confidence is.. (?)

I personally believe body language stems from your belief in ones self. If you are content with the person you are and confident about your own opinion then this will resonate in your actions and hence your body language. I know many people work purely on behaviour and try to make sure they are sitting in a certain way and moving their hands in a certain way but there is nothing like being confident in ones self and letting that confidence resonate itself. 

Seating straight..Eye contact..Right facial Expression of your words..Smile..Laugh..

Smiling, tilting face, repeating approve movement.

certainly, Body language implicate the confidence of a candidate

Eye contact and smiling and I think not to over move your hands